import hashlib
import os
import urllib
import warnings
from typing import Union, List
from pkg_resources import packaging

import torch
from PIL import Image
from torchvision.transforms import Compose, Resize, ToTensor, Normalize
from tqdm import tqdm
import numpy as np

from .build_model import build_model
from .simple_tokenizer import SimpleTokenizer as _Tokenizer

try:
    from torchvision.transforms import InterpolationMode
    BICUBIC = InterpolationMode.BICUBIC
except ImportError:
    BICUBIC = Image.BICUBIC


if packaging.version.parse(torch.__version__) < packaging.version.parse("1.7.1"):
    warnings.warn("PyTorch version 1.7.1 or higher is recommended")


__all__ = ["available_models", "load", "tokenize", "encode_text_with_prompt_ensemble",
           "get_similarity_map", "clip_feature_surgery", "similarity_map_to_points"]
_tokenizer = _Tokenizer()

_MODELS = {
    "RN50": "https://openaipublic.azureedge.net/clip/models/afeb0e10f9e5a86da6080e35cf09123aca3b358a0c3e3b6c78a7b63bc04b6762/RN50.pt",
    "RN101": "https://openaipublic.azureedge.net/clip/models/8fa8567bab74a42d41c5915025a8e4538c3bdbe8804a470a72f30b0d94fab599/RN101.pt",
    "RN50x4": "https://openaipublic.azureedge.net/clip/models/7e526bd135e493cef0776de27d5f42653e6b4c8bf9e0f653bb11773263205fdd/RN50x4.pt",
    "RN50x16": "https://openaipublic.azureedge.net/clip/models/52378b407f34354e150460fe41077663dd5b39c54cd0bfd2b27167a4a06ec9aa/RN50x16.pt",
    "RN50x64": "https://openaipublic.azureedge.net/clip/models/be1cfb55d75a9666199fb2206c106743da0f6468c9d327f3e0d0a543a9919d9c/RN50x64.pt",
    "ViT-B/32": "https://openaipublic.azureedge.net/clip/models/40d365715913c9da98579312b702a82c18be219cc2a73407c4526f58eba950af/ViT-B-32.pt",
    "ViT-B/16": "https://openaipublic.azureedge.net/clip/models/5806e77cd80f8b59890b7e101eabd078d9fb84e6937f9e85e4ecb61988df416f/ViT-B-16.pt",
    "ViT-L/14": "https://openaipublic.azureedge.net/clip/models/b8cca3fd41ae0c99ba7e8951adf17d267cdb84cd88be6f7c2e0eca1737a03836/ViT-L-14.pt",
    "ViT-L/14@336px": "https://openaipublic.azureedge.net/clip/models/3035c92b350959924f9f00213499208652fc7ea050643e8b385c2dac08641f02/ViT-L-14-336px.pt",
    "CS-RN50": "https://openaipublic.azureedge.net/clip/models/afeb0e10f9e5a86da6080e35cf09123aca3b358a0c3e3b6c78a7b63bc04b6762/RN50.pt",
    "CS-RN101": "https://openaipublic.azureedge.net/clip/models/8fa8567bab74a42d41c5915025a8e4538c3bdbe8804a470a72f30b0d94fab599/RN101.pt",
    "CS-RN50x4": "https://openaipublic.azureedge.net/clip/models/7e526bd135e493cef0776de27d5f42653e6b4c8bf9e0f653bb11773263205fdd/RN50x4.pt",
    "CS-RN50x16": "https://openaipublic.azureedge.net/clip/models/52378b407f34354e150460fe41077663dd5b39c54cd0bfd2b27167a4a06ec9aa/RN50x16.pt",
    "CS-RN50x64": "https://openaipublic.azureedge.net/clip/models/be1cfb55d75a9666199fb2206c106743da0f6468c9d327f3e0d0a543a9919d9c/RN50x64.pt",
    "CS-ViT-B/32": "https://openaipublic.azureedge.net/clip/models/40d365715913c9da98579312b702a82c18be219cc2a73407c4526f58eba950af/ViT-B-32.pt",
    "CS-ViT-B/16": "https://openaipublic.azureedge.net/clip/models/5806e77cd80f8b59890b7e101eabd078d9fb84e6937f9e85e4ecb61988df416f/ViT-B-16.pt",
    "CS-ViT-L/14": "https://openaipublic.azureedge.net/clip/models/b8cca3fd41ae0c99ba7e8951adf17d267cdb84cd88be6f7c2e0eca1737a03836/ViT-L-14.pt",
    "CS-ViT-L/14@336px": "https://openaipublic.azureedge.net/clip/models/3035c92b350959924f9f00213499208652fc7ea050643e8b385c2dac08641f02/ViT-L-14-336px.pt",
}


def _download(url: str, root: str):
    os.makedirs(root, exist_ok=True)
    filename = os.path.basename(url)

    expected_sha256 = url.split("/")[-2]
    download_target = os.path.join(root, filename)

    if os.path.exists(download_target) and not os.path.isfile(download_target):
        raise RuntimeError(f"{download_target} exists and is not a regular file")

    if os.path.isfile(download_target):
        if hashlib.sha256(open(download_target, "rb").read()).hexdigest() == expected_sha256:
            return download_target
        else:
            warnings.warn(f"{download_target} exists, but the SHA256 checksum does not match; re-downloading the file")

    with urllib.request.urlopen(url) as source, open(download_target, "wb") as output:
        with tqdm(total=int(source.info().get("Content-Length")), ncols=80, unit='iB', unit_scale=True, unit_divisor=1024) as loop:
            while True:
                buffer = source.read(8192)
                if not buffer:
                    break

                output.write(buffer)
                loop.update(len(buffer))

    if hashlib.sha256(open(download_target, "rb").read()).hexdigest() != expected_sha256:
        raise RuntimeError(f"Model has been downloaded but the SHA256 checksum does not not match")

    return download_target


def _convert_image_to_rgb(image):
    return image.convert("RGB")


def _transform(n_px):
    return Compose([
        Resize((n_px, n_px), interpolation=BICUBIC),
        #CenterCrop(n_px), # rm center crop to explain whole image
        _convert_image_to_rgb,
        ToTensor(),
        Normalize((0.48145466, 0.4578275, 0.40821073), (0.26862954, 0.26130258, 0.27577711)),
    ])


def available_models() -> List[str]:
    """Returns the names of available CLIP models"""
    return list(_MODELS.keys())


def load(name: str, device: Union[str, torch.device] = "cuda" if torch.cuda.is_available() else "cpu", jit: bool = False, download_root: str = None):
    """Load a CLIP model

    Parameters
    ----------
    name : str
        A model name listed by `clip.available_models()`, or the path to a model checkpoint containing the state_dict

    device : Union[str, torch.device]
        The device to put the loaded model

    jit : bool
        Whether to load the optimized JIT model or more hackable non-JIT model (default).

    download_root: str
        path to download the model files; by default, it uses "~/.cache/clip"

    Returns
    -------
    model : torch.nn.Module
        The CLIP model

    preprocess : Callable[[PIL.Image], torch.Tensor]
        A torchvision transform that converts a PIL image into a tensor that the returned model can take as its input
    """
    if name in _MODELS:
        model_path = _download(_MODELS[name], download_root or os.path.expanduser("~/.cache/clip"))
    elif os.path.isfile(name):
        model_path = name
    else:
        raise RuntimeError(f"Model {name} not found; available models = {available_models()}")

    with open(model_path, 'rb') as opened_file:
        try:
            # loading JIT archive
            model = torch.jit.load(opened_file, map_location=device if jit else "cpu").eval()
            state_dict = None
        except RuntimeError:
            # loading saved state dict
            if jit:
                warnings.warn(f"File {model_path} is not a JIT archive. Loading as a state dict instead")
                jit = False
            state_dict = torch.load(opened_file, map_location="cpu")

    if not jit:
        model = build_model(name, state_dict or model.state_dict()).to(device)
        if str(device) == "cpu":
            model.float()
        return model, _transform(model.visual.input_resolution)

    # patch the device names
    device_holder = torch.jit.trace(lambda: torch.ones([]).to(torch.device(device)), example_inputs=[])
    device_node = [n for n in device_holder.graph.findAllNodes("prim::Constant") if "Device" in repr(n)][-1]

    def patch_device(module):
        try:
            graphs = [module.graph] if hasattr(module, "graph") else []
        except RuntimeError:
            graphs = []

        if hasattr(module, "forward1"):
            graphs.append(module.forward1.graph)

        for graph in graphs:
            for node in graph.findAllNodes("prim::Constant"):
                if "value" in node.attributeNames() and str(node["value"]).startswith("cuda"):
                    node.copyAttributes(device_node)

    model.apply(patch_device)
    patch_device(model.encode_image)
    patch_device(model.encode_text)

    # patch dtype to float32 on CPU
    if str(device) == "cpu":
        float_holder = torch.jit.trace(lambda: torch.ones([]).float(), example_inputs=[])
        float_input = list(float_holder.graph.findNode("aten::to").inputs())[1]
        float_node = float_input.node()

        def patch_float(module):
            try:
                graphs = [module.graph] if hasattr(module, "graph") else []
            except RuntimeError:
                graphs = []

            if hasattr(module, "forward1"):
                graphs.append(module.forward1.graph)

            for graph in graphs:
                for node in graph.findAllNodes("aten::to"):
                    inputs = list(node.inputs())
                    for i in [1, 2]:  # dtype can be the second or third argument to aten::to()
                        if inputs[i].node()["value"] == 5:
                            inputs[i].node().copyAttributes(float_node)

        model.apply(patch_float)
        patch_float(model.encode_image)
        patch_float(model.encode_text)

        model.float()

    return model, _transform(model.input_resolution.item())


def tokenize(texts: Union[str, List[str]], context_length: int = 77, truncate: bool = False) -> Union[torch.IntTensor, torch.LongTensor]:
    """
    Returns the tokenized representation of given input string(s)

    Parameters
    ----------
    texts : Union[str, List[str]]
        An input string or a list of input strings to tokenize

    context_length : int
        The context length to use; all CLIP models use 77 as the context length

    truncate: bool
        Whether to truncate the text in case its encoding is longer than the context length

    Returns
    -------
    A two-dimensional tensor containing the resulting tokens, shape = [number of input strings, context_length].
    We return LongTensor when torch version is <1.8.0, since older index_select requires indices to be long.
    """
    if isinstance(texts, str):
        texts = [texts]

    sot_token = _tokenizer.encoder["<|startoftext|>"]
    eot_token = _tokenizer.encoder["<|endoftext|>"]
    all_tokens = [[sot_token] + _tokenizer.encode(text) + [eot_token] for text in texts]
    if packaging.version.parse(torch.__version__) < packaging.version.parse("1.8.0"):
        result = torch.zeros(len(all_tokens), context_length, dtype=torch.long)
    else:
        result = torch.zeros(len(all_tokens), context_length, dtype=torch.int)

    for i, tokens in enumerate(all_tokens):
        if len(tokens) > context_length:
            if truncate:
                tokens = tokens[:context_length]
                tokens[-1] = eot_token
            else:
                raise RuntimeError(f"Input {texts[i]} is too long for context length {context_length}")
        result[i, :len(tokens)] = torch.tensor(tokens)

    return result


def encode_text_with_prompt_ensemble(model, texts, device, prompt_templates=None):

    # using default prompt templates for ImageNet
    if prompt_templates == None:
        prompt_templates = ['a bad photo of a {}.', 'a photo of many {}.', 'a sculpture of a {}.', 'a photo of the hard to see {}.', 'a low resolution photo of the {}.', 'a rendering of a {}.', 'graffiti of a {}.', 'a bad photo of the {}.', 'a cropped photo of the {}.', 'a tattoo of a {}.', 'the embroidered {}.', 'a photo of a hard to see {}.', 'a bright photo of a {}.', 'a photo of a clean {}.', 'a photo of a dirty {}.', 'a dark photo of the {}.', 'a drawing of a {}.', 'a photo of my {}.', 'the plastic {}.', 'a photo of the cool {}.', 'a close-up photo of a {}.', 'a black and white photo of the {}.', 'a painting of the {}.', 'a painting of a {}.', 'a pixelated photo of the {}.', 'a sculpture of the {}.', 'a bright photo of the {}.', 'a cropped photo of a {}.', 'a plastic {}.', 'a photo of the dirty {}.', 'a jpeg corrupted photo of a {}.', 'a blurry photo of the {}.', 'a photo of the {}.', 'a good photo of the {}.', 'a rendering of the {}.', 'a {} in a video game.', 'a photo of one {}.', 'a doodle of a {}.', 'a close-up photo of the {}.', 'a photo of a {}.', 'the origami {}.', 'the {} in a video game.', 'a sketch of a {}.', 'a doodle of the {}.', 'a origami {}.', 'a low resolution photo of a {}.', 'the toy {}.', 'a rendition of the {}.', 'a photo of the clean {}.', 'a photo of a large {}.', 'a rendition of a {}.', 'a photo of a nice {}.', 'a photo of a weird {}.', 'a blurry photo of a {}.', 'a cartoon {}.', 'art of a {}.', 'a sketch of the {}.', 'a embroidered {}.', 'a pixelated photo of a {}.', 'itap of the {}.', 'a jpeg corrupted photo of the {}.', 'a good photo of a {}.', 'a plushie {}.', 'a photo of the nice {}.', 'a photo of the small {}.', 'a photo of the weird {}.', 'the cartoon {}.', 'art of the {}.', 'a drawing of the {}.', 'a photo of the large {}.', 'a black and white photo of a {}.', 'the plushie {}.', 'a dark photo of a {}.', 'itap of a {}.', 'graffiti of the {}.', 'a toy {}.', 'itap of my {}.', 'a photo of a cool {}.', 'a photo of a small {}.', 'a tattoo of the {}.', 'there is a {} in the scene.', 'there is the {} in the scene.', 'this is a {} in the scene.', 'this is the {} in the scene.', 'this is one {} in the scene.']

    text_features = []
    for t in texts:
        prompted_t = [template.format(t) for template in prompt_templates]
        prompted_t = tokenize(prompted_t).to(device)
        class_embeddings = model.encode_text(prompted_t)
        class_embeddings /= class_embeddings.norm(dim=-1, keepdim=True)
        class_embedding = class_embeddings.mean(dim=0)
        class_embedding /= class_embedding.norm()
        text_features.append(class_embedding)
    text_features = torch.stack(text_features, dim=1).to(device).t()

    return text_features


def get_similarity_map(sm, shape):

    # min-max norm
    sm = (sm - sm.min(1, keepdim=True)[0]) / (sm.max(1, keepdim=True)[0] - sm.min(1, keepdim=True)[0])

    # reshape
    side = int(sm.shape[1] ** 0.5) # square output
    sm = sm.reshape(sm.shape[0], side, side, -1).permute(0, 3, 1, 2)

    # interpolate
    sm = torch.nn.functional.interpolate(sm, shape, mode='bilinear')
    sm = sm.permute(0, 2, 3, 1)
    
    return sm


def clip_feature_surgery(image_features, text_features, redundant_feats=None, t=2):

    if redundant_feats != None:
        similarity = image_features @ (text_features - redundant_feats).t()

    else:
        # weights to restrain influence of obvious classes on others
        prob = image_features[:, :1, :] @ text_features.t()
        prob = (prob * 2).softmax(-1)
        w = prob / prob.mean(-1, keepdim=True)

        # element-wise multiplied features
        b, n_t, n_i, c = image_features.shape[0], text_features.shape[0], image_features.shape[1], image_features.shape[2]
        feats = image_features.reshape(b, n_i, 1, c) * text_features.reshape(1, 1, n_t, c)
        feats *= w.reshape(1, 1, n_t, 1)
        redundant_feats = feats.mean(2, keepdim=True) # along cls dim
        feats = feats - redundant_feats
        
        # sum the element-wise multiplied features as cosine similarity
        similarity = feats.sum(-1)

    return similarity


# sm shape N_t
def similarity_map_to_points(sm, shape, t=0.8, down_sample=2):
    side = int(sm.shape[0] ** 0.5)
    sm = sm.reshape(1, 1, side, side)

    # down sample to smooth results
    down_side = side // down_sample
    sm = torch.nn.functional.interpolate(sm, (down_side, down_side), mode='bilinear')[0, 0, :, :]
    h, w = sm.shape
    sm = sm.reshape(-1)

    sm = (sm - sm.min()) / (sm.max() - sm.min())
    rank = sm.sort(0)[1]
    scale_h = float(shape[0]) / h
    scale_w = float(shape[1]) / w

    num = min((sm >= t).sum(), sm.shape[0] // 2)
    labels = np.ones(num * 2).astype('uint8')
    labels[num:] = 0
    points = []

    # positives
    for idx in rank[-num:]:
        x = min((idx % w + 0.5) * scale_w, shape[1] - 1) # +0.5 to center
        y = min((idx // w + 0.5) * scale_h, shape[0] - 1)
        points.append([int(x.item()), int(y.item())])

    # negatives
    for idx in rank[:num]:
        x = min((idx % w + 0.5) * scale_w, shape[1] - 1)
        y = min((idx // w + 0.5) * scale_h, shape[0] - 1)
        points.append([int(x.item()), int(y.item())])

    return points, labels
